Modeling absorption and segregation of magnesium and cadmium ions to calcite surfaces:: Introducing MgCO3 and CdCO3 potential models
Modeling absorption and segregation of magnesium and cadmium ions to calcite surfaces:: Introducing MgCO3 and CdCO3 potential models
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DOI：
10.1063/1.480979
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发表时间：
2000-03-01
影响因子：
4.4
通讯作者：
Parker, SC
中科院分区：
文献类型：
--
作者：
de Leeuw, NH;Parker, SC
我们介绍了一个潜在的模型MgCO 3和CdCO 3再现实验结构参数和解决方案的能量。我们采用原子模拟技术来模拟镁和镉离子在方解石低折射率表面的吸附和分离。镁离子和镉离子都在表面从溶液中吸收。吸收能量是表面依赖性的，由于不同的表面的不同的弛豫，和离子依赖性与较小尺寸的镁离子显示较大的弛豫。镁的吸收能大于镉，这主要是由于水分子与镁取代表面的配位更紧密。镉离子比镁离子更容易分离到大块晶体中，而镁离子更喜欢留在表面。然而，在一些表面的第二层和进一步的层中的阳离子的分离能是正的，这表明一旦碳酸钙层已经过度生长取代的表面层，分离到本体是可能的。(C)2000年美国物理学会。[S0021-9606（00）70608-8]。
We introduce a potential model for MgCO3 and CdCO3 which reproduces experimental structural parameters and solution energies. We employed atomistic simulation techniques to model the absorption and segregation of magnesium and cadmium ions to the low-index surfaces of calcite. Both magnesium and cadmium ions absorb at the surfaces from solution. The absorption energies are surface dependent, due to distinct relaxations of the different surfaces, and ion dependent with the smaller sized magnesium ion showing larger relaxations. The absorption energies are larger for magnesium than for cadmium, mainly due to the closer coordination of the water molecules to the magnesium substituted surfaces. The cadmium ions segregate to the bulk crystal more easily than the magnesium ions which prefer to remain at the surface. However, segregation energies for both cations in second and further layers of some surfaces are positive, indicating that once a calcium carbonate layer has overgrown the substituted surface layer, segregation to the bulk is energetically possible. (C) 2000 American Institute of Physics. [S0021-9606(00)70608-8].